Audio/video reproducing systems are widely used in many consumer and commercial environments. As is well known to those having skill in the art, an audio/video reproducing system includes an audio/video electronics system that is configured to produce audio/video electrical signals from an audio/video program source. The audio/video program source may include a live program source such as AM/FM radio, satellite radio, broadcast television, cable radio, cable television and/or other conventional live program sources. The audio/video program source may also include stored audio/video program sources such as hard drives, CDs, DVDs, tape, solid state storage and/or other conventional stored audio/video program sources. An audio/video reproducing system may also include an electrical-to-audio/video transducer, including one or more displays (such as a television or monitor) and/or one or more speakers (loudspeakers and/or earspeakers) that are configured to convert the audio/video signals into sounds and/or images. Audio/video reproducing systems include audio only, video only and combined audio and video reproducing systems.
As is also well known to those having skill in the art, an audio/video reproducing system may be fixed, mounted in a vehicle and/or portable. Fixed audio/video reproducing systems may be provided in a home or commercial environment, and may include home stereo, home theater and/or computer-based audio/video systems. Vehicular audio/video reproducing systems can include vehicle audio and/or vehicle video systems. Finally, portable audio/video reproducing systems can include well known disc-based or solid state storage-based systems and/or over-the-air reception systems, marketed, for example, by Sony under the Walkman™ designator, or by Apple under the iPod™ designator.
Finally, audio/video reproducing systems may be standalone systems or may integrated with other systems. Examples of integrated audio/video reproducing systems include home audio/video reproducing systems that are integrated with home automation systems, vehicular audio/video reproducing systems that are integrated with vehicular navigation systems, and portable audio/video reproducing systems that are integrated with cell phones or Personal Digital Assistants (PDAs). The design of audio/video reproducing systems is well known to those having skill in the art, and need not be described further herein.
It is known to control the sound volume of an audio/video reproducing system in response to changes in ambient noise. Ambient noise-sensitive audio/video systems are often used, for example, in vehicular audio systems to compensate for changes in road noise or other ambient conditions. Automatic volume control systems that are responsive to ambient conditions are described, for example, in U.S. Pat. Nos. 4,306,115; 4,553,257; 4,628,526; 5,666,426; 5,907,622; 6,169,807; 6,370,254; and U.S. Patent Application Publications 2003/0013495 and 2005/0175194. It is also known to increase or decrease the brightness of a video display, such as a television, in response to ambient lighting conditions, so as to maintain acceptable contrast in the display under varying ambient lighting conditions.